Animals account for almost 20 percent of the world's food consumption, and animal-based food products are a major source of revenue throughout the world. In the United States alone, beef production is the fourth largest manufacturing industry and accounts for nearly 25 percent of the farm sector cash receipts and seven percent of supermarket sales each year.
Significant improvements in animal performance, efficiency and carcass and meat quality have been made over the years through the application of standard animal breeding and selection techniques. However, such classical animal breeding techniques require several years of genetic evaluation of performance records on individual animals and their relatives and are therefore very expensive. Other efforts have been made to improve productivity and quality through the application of such management practices as the use of feed additives, animal hormonal implants and chemotherapeutics. However, there is significant political and regulatory resistance to the introduction and use of such methodologies. Such methodologies are also non-heritable and need to be applied differently in every production system.
There is a need for methods that allow relatively easy and more efficient selection and breeding of farm animals that have an advantage for a heritable trait of the polled phenotype. The economic significance of the use of genetic markers that are associated with specific economically important traits in livestock through marker-assisted selection cannot therefore be over-emphasized.
The presence of horns within commercial cattle populations increases the chances of injuries, particularly during transportation. Quality defects in the form of bruised carcasses, arising from these injuries, cost the industry millions of dollars every year. Producers and packers ranked bruising as one of their top ten concerns for the fed steer and heifer industry in the National Beef Quality Audit-2000. Bruising was also the number two “quality challenge” of the market cow and bull beef industry. Dehorning cattle provides a recurrent managerial solution to the problem. However, there are negative stress effects to the animal, and concerns that dehorning may be an inhumane treatment.
The polled (hornless) condition in cattle has existed since domestication, and it has been selected by breeders because of its economic importance and ease of management. A single, dominant mutation is believed to cause the polled phenotype, but the causative gene remains unknown.
In 1991, Bricker and Church (Abst. 36th annual meeting of the Genetics Society of Canada [Kingston, Ontario. Jun. 11-14, 1991]) reviewed the co-segregaton of Poll with 1:29 translocation in Charolais cattle and found that Poll is very close to the centromere of chromosome 1. Georges et al., Nature Genetics 4: 206-210 (1993) localized the polled locus to the centromeric end of the bovine chromosome 1. This location was further refined by Brenneman et al., J. Heredity 87:156-161 (1996) to a region proximal to the centromere and 4.9 cM (centimorgan) from microsatellite TGLA49. Using the same population, the interval was further refined to a 1.7 megabase region between IFNAR and SOD1. Recently Drogemuller et al., Mammalian Genome 16: 613-620 (2005) localized the polled locus to a 1.0 megabase region between markers BM6438 and RP42-218J17_MS1 (FIG. 43).
Polymorphisms in candidate genes that show association with specific economically relevant traits (ERT) may be useful markers for marker-assisted selection. It remains advantageous to provide SNPs, so that a more accurate prediction can be made of the Polled phenotype of an animal, and also enable a business method that provides for increased productivity in livestock cattle, as well as providing access to various records of the animals and allows comparisons with expected or desired goals with regard to the quality and quantity of animals produced.
Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.